Latest revision as of 08:27, 15 November 2008

Contents

Description

This section describes the technology of DMA copy of kernel on startup. It's necessary to copy binary images, such as a kernel image, file system images, and so on, from ROM to RAM on bootup if XIP isn't used. In this case, using DMA transfer is very efficient to save the time and CPU resources.

Rationale

This feature is important to CELF because it reduces bootup time significantly.

In the normal boot case, the kernel image whose size is 1.7MB around is copied from ROM to RAM by CPU at firmware init. On the other hand, DMA copy is used in the fast boot case and it reduces about 180 milliseconds.

It owes much to the potentiality of FR-V processor, but it's worthy of consideration to use such a hardware assist feature for reducing bootup time.